Thus the total energy of the nerve cell or the neuron may be divided into normal dynamic energy, reserve energy, static energy, and organic or necrotic energy. The various nervous and mental diseases may thus be correlated with the flow and ebb of neuron energy, with the physiological and pathological processes that take place in the neuron in the course of its activity and reactions to the stimuli of the external and internal environment. The various levels of neuron energy may be represented by the diagram on page 336. Static energy is indicated by the diagram NWFI. By _organic energy_ is meant that energy contained in the very structure of the tissues of the neuron, not as yet decomposed into their inorganic constituents. This is indicated by diagram IFGH. These phases of neuron energy are not different kinds of energy, in the sense of being distinct entities; they merely represent progressive phases or stages of the same process of neuron activity. _Liberation_ of neuron energy is correlative with active psychic and physical manifestations. Hence states of the nervous system corresponding to liberations of energy are designated as _waking states_. _Restitution_ of expended energy or arrest of liberation of neuron energy goes hand in hand with _passive_ conditions of the nervous system; hence states of restitution or arrest of energy are termed collectively _sleeping states_. [Illustration: DIAGRAM IV] The ascending arrow, indicating the process of restitution of energy, corresponds to the ascending arrow on the right, indicating the parallel psychomotor sleeping states. The descending arrows indicate physiological and pathological processes of liberation of energy, and also their concomitant psychomotor waking states. “Ascending” and “descending” mean the rise and fall of the amount of neuron energy, taking the upper level of dynamic energy as the starting point. Briefly stated, _descent_ means _liberation_ of energy with its concomitant, psychomotor, waking states. _Ascent_ means _restitution_ of energy with its parallel sleeping states. The cycles in dynamic energy correspond to the physiological manifestations of the nervous system in the activity and rest of the individual in normal daily life. Concomitant with the expenditure of dynamic energy of the neurons, the individual passes through the active normal waking state, and hand in hand with the restitution of this expended energy, he passes through the sleeping states of normal daily life.